The wireless interface Media Access Control (MAC) protocol layer of the Evolved Universal Terrestrial Radio Access Network (E-UTRAN, which is comprised of base station eNBs, and thus can also be referred to as base station eNBs) of the third generation mobile communication Long Term Evolution (LTE) system has a Scheduling/Priority Handling functional entity, wherein the scheduling function supports dynamic scheduling and semi-persistent scheduling (or can be referred to as semi-static scheduling).
The Dynamic Scheduling refers to that the E-UTRAN can dynamically allocate resources including the Physical Resource Block (PRB) and Modulation and Coding Scheme (MCS) etc. to an user equipment (UE) in each Transmit Time Interval (TTI, which corresponds to one subframe) through a Cell Radio Network Temporary Identifier (C-RNTI) on the Physical Downlink Control Channel (PDCCH) for the UE to receive/send data, wherein the uplink uses Downlink Control Information (DCI) format 0 and the downlink uses DCI format 1 to indicate the scheduling information, as shown in Table 1 and Table 2, and the main difference between them is that as the downlink Hybrid ARQ (HARQ) is an asynchronous HARQ, the downlink HARQ needs the indication of the process number of the HARQ, while as the uplink HARQ is a synchronous HARQ, the uplink HARQ does not need the indication of the identification. Both HARQ first transmission and HARQ retransmission of the UE can use the dynamic scheduling.
TABLE 1the primary definition domain of the DCI format 0namedescriptionassignment informationindicating the frequency domain resourcesof a Resource Blockwhich can be used by the UEModulation and Codingindicating the modulation mode and the codingScheme (MCS)rate which should be used by the UE to senddataNew Data Indicatorindicating whether the UE sends new data or(NDI)retransmits old dataUplink indexconfiguration 0 of the TDD mode, indicatingwhich uplink subframe the uplink grant is usedforDownlink Assignmentconfigurations 1-6 of the TDD mode,Index (DAI)indicating the subframe of the HARQ feedback
TABLE 2the primary definition domain of the DCI format 1namedescriptionresourceindicating the type of the resource allocationallocationHeaderAssignmentindicating frequency domain resources which can beinformation ofused by the UEResource BlockMCSindicating that the modulation mode and the coding ratewhich should be used by the UE to send dataHARQ processindicating the HARQ process which is used by the UEnumberNDIindicating whether the UE sends new data or retransmitsold dataRedundancyindicating the HARQ RV which is sent by the UEVersion (RV)DAIconfigurations 1-6 of the TDD mode, indicating thesubframe of the HARQ feedback
The Semi-persistent Scheduling (SPS) refers to that the E-UTRAN can allocate semi-persistent resources including Physical Resource Block (PRB), Modulation and Coding Scheme (MCS) etc. to an user equipment (UE) through a Semi-Persistent Scheduling C-RNTI (C-RNTI) on the Physical Downlink Control Channel (PDCCH) for the UE to receive or send data. In the SPS, the HARQ first transmission of the UE uses semi-persistent resources, and the HARQ retransmission uses dynamic scheduling resources. The semi-persistent resources are repeated according to the configured period, and when the UE is configured with subframes of semi-persistent resources, if the UE does not detect the C-RNTI thereof on the PDCCH, the UE receives or sends data on the corresponding subframes according to the semi-persistent resources. When the UE is configured with semi-persistent resources, if the UE detect the C-RNTI thereof on the PDCCH, the UE uses dynamic resources indicated by the PDCCH to override the semi-persistent resources on the corresponding subframes.
Typically, the semi-persistent scheduling is applied to VoIP services, and the period of the semi-persistent resources allocated for the semi-persistent scheduling is 20 ms. The E-UTRAN configures semi-persistent scheduling parameters including semi-persistent scheduling Cell-Radio Network Temporal Identifier (C-RNTI), downlink semi-persistent scheduling configuration, uplink semi-persistent scheduling configuration etc. for the UE through Radio Resource Control (RRC) signaling. The downlink or uplink semi-persistent scheduling parameters can be configured respectively. The downlink semi-persistent scheduling parameters include information such as downlink semi-persistent scheduling period, the number of reserved HARQ processes, Physical Uplink Control Channel (PUCCH) feedback resources. The uplink semi-persistent scheduling parameters include information such as uplink semi-persistent scheduling period, implicit releasing parameters, Physical Uplink Shared Channel (PUSCH) related parameters, and further include two-period configuration information for the TDD mode. The E-UTRAN enables/disables downlink or uplink semi-persistent scheduling through the RRC signaling, and when the downlink or uplink semi-persistent scheduling is disabled, the corresponding semi-persistent resources are released. The LTE Frequency Divided Duplex (FDD) mode supports at most one period on the downlink or uplink respectively. The Time Divided Duplex (TDD) mode only support one period on the downlink and supports the two-period configuration on the uplink to avoid the conflict of the semi-persistent resources at the time of HARQ retransmission and HARQ first transmission. For the downlink, the E-UTRAN configures the number of HARQ processes which are reserved by the semi-persistent scheduling for the UE through the RRC, and the dynamic scheduling can share the HARQ processes which are reserved for the semi-persistent scheduling. For the uplink, the dynamic scheduling and semi-persistent scheduling can also share the same HARQ process. The E-UTRAN activates semi-persistent resources for the UE through the PDCCH. In order to reduce the complexity of the semi-persistent scheduling, the semi-persistent resources are allocated to the whole UE instead of a certain specific service. The downlink or uplink is configured with one semi-persistent resource (including information such as PRB, MCS etc.) at most respectively, and the semi-persistent resources occur periodically according to the downlink or uplink semi-persistent scheduling which is configured by the RRC signaling. The E-UTRAN explicitly releases the downlink or uplink semi-persistent resources of the UE through the PDCCH. For the uplink, implicitly releasing the semi-persistent resources is also supported, and the UE triggers the release of the semi-persistent resources according to a number of successive new Media Access Control Protocol Data Units (MAC PDUs) which does not include Media Access Control Service Data Unit (MAC SDU).
In order to satisfy the increasing demand for large bandwidth high speed mobile access, the Third Generation Partnership Projects (3GPP) provides a Long-Term Evolution Advanced (LTE-Advanced) standard. The LTE-Advanced reserves the LTE core for the evolution of the Long-Term Evolution (LTE), and on that basis, uses a series of technologies to expand the frequency domain and the spatial domain, so as to achieve the purposes of enhancing spectrum efficiency and increasing system capacity and so on. The Radio Relay technology is one of the LTE-Advanced technologies, and is intended to expand the coverage of the cell, reduce the dead region in the communications, balance the load, transfer the services of the hot spots, and save transmitting power of the terminal (or is referred to as User Equipment (UE)). As shown in FIG. 1, some new Relay-Nodes (RNs) are added between the Donor-eNB and the UE. These newly added RNs are wirelessly connected to the Donor-eNB, and there is no wired connection to the transmission network, wherein the wireless links between the Donor-eNB and the RNs are referred to as backhaul links, and the wireless links between the RNs and the UE is referred to as access links. The downlink data firstly reaches the Donor-eNB, and then is transmitted to the RN, which then transmits the downlink data to the UE; and it is opposite for the uplink.
In order to configure resources of the backhaul link, the Relay Physical Downlink Control Channel (R-PDCCH), Physical Share Channel (R-PDSCH) and Physical Uplink Share Channel are defined. The R-PDCCH is used to dynamically or semi-statically allocate the R-PDSCH resources and R-PUSCH resources, wherein the R-PDSCH resources are used to transmit downlink data of the backhaul link, and the R-PUSCH resources are used to transmit uplink data of the backhaul link.
The difference between the R-PDCCH and the PDCCH on indicating resource allocation is that the R-PDCCH can indicate downlink resources of multiple subsequent subframes in addition to the downlink resources of the current subframe, moreover, the R-PDCCH can also indicate uplink resources of multiple subsequent subframes. However, existing resource allocation methods are only suitable to schedule a resource of a single subframe, and thus, there is a need of a new scheduling method for the R-PDCCH to schedule resources of multiple subframes.